Learn to forecast your building's energy usage and attract more customers.
Given persistent challenges facing the construction and real estate industries, developers and contractors are relying more than ever on architects and engineers to identify potential operating efficiencies in new and existing buildings. Efficiencies achieved through sustainable design and use of green materials can make buildings more environmentally friendly. But the means of achieving those efficiencies are almost always driven by the long-term bottom-line economic benefits that high-performance design delivers.
These benefits touch nearly everyone associated building a structure. Energy efficient buildings are less costly to operate, and lower costs allow owners to offer attractive lease rates to potential tenants. The more square footage owned and occupied, the greater the savings for both the owner and the tenants.
Today's workers are more sophisticated in their knowledge of environmental issues, including those associated with their workplace. Some even make the physical space in which they work a key consideration when deciding where to work, and for whom. Many employers, meanwhile, are becoming increasingly aware of possible correlations between sustainable design and its effects on worker productivity and absenteeism. Several studies now underway seek to quantify this correlation. If proven, then owners of high-performing buildings will have an especially powerful marketing tool at their disposal.
Beyond the private sector, local governments also stand to gain from energy-efficient commercial building inventories, since modern, efficient structures are a key selling point to attract businesses and the tax dollars they generate.
Energy Modeling Defined
Thus, the challenge for developers and contractors comes back to identifying potential efficiencies in new or existing structures at a reasonable cost. Thankfully, software for modeling energy dynamics makes it possible for architects and engineers to do just that by designing efficient buildings at the outset of a project, or to the extent possible, by integrating efficiencies into existing buildings.
The process, called energy modeling, forecasts how much energy a building could potentially use based on construction materials and methods, its mechanical systems, its orientation on the site and specific site characteristics, the anticipated occupant requirements and average local climate conditions.
It gauges how specific systems within a building interact. By predicting actual energy use, energy modeling helps to determine the best possible integration of systems. This, in turn, points designers toward optimal strategies to enhance overall building system performance.
Before the arrival of modeling software, energy modeling was a difficult, time-consuming task that did not really offer a viable cost-saving opportunity for developers and contractors-especially on smaller-scale projects. Today, it is increasingly used to design high-performance buildings and identify efficiencies in existing structures.
Ideally, energy modeling should be implemented at the earliest stages of large-scale new construction. But it also can be used to pinpoint opportunities in projects that are smaller in size, as well as existing buildings. In most cases, it is wise for architects and engineers to consider lighting and HVAC systems first.
Lighting Strategies
Achieving proper daylighting is essential to delivering energy-efficient buildings. Doing so entails reducing the lumen power density (LPD), or the amount of energy utilized per square foot to illuminate a space. Experts agree that the best way to do this is by harvesting natural daylight. Artificial light can be reduced substantially-in some cases, by more than 50 percent, given proper automated lighting control and daylight harvesting techniques. Heat gain from that light is also reduced, which then reduces the HVAC load needed to cool a space.
With energy modeling, a certified design professional can simulate daylight conditions for buildings by inputting data into software that tracks the sun's movement based on specific seasonal and geographical factors. This gives everyone involved, from designers and building owners to contractors, a perspective on how that building will perform relative to its orientation to the sun. It also provides important information about ways in which the resulting heat gain and daylight harvesting methods can be used to achieve additional efficiencies.
HVAC Strategies
For new buildings in particular, energy modeling enables designers to compare various mechanical systems at the beginning of a project, before final design is completed.
Design and equipment variables are linked to estimated occupant energy requirements, including electrical load and desired indoor comfort levels. Local climate and temperature data is then applied. The results predict specific ways in which that building will utilize energy. From that, designers can estimate its annual operating costs.
Tangible Benefits of Energy Modeling
For new and existing buildings alike, a strong case can be made for the value of energy modeling. From planning a new project to maximizing the efficiencies possible in existing buildings, energy modeling makes it possible for architects and engineers to set specific energy efficiency goals for their clients. This makes it easier to compare different building and energy use strategies and determine how they impact overall operational costs.
Energy modeling can also be used to help projects attain LEED certification. Though LEED points are not allocated specifically to energy modeling, it can be applied to one of the four "Innovation" credits that are available as part of the certification process. Additionally, the precise nature of energy modeling helps to better measure specific lighting and HVAC usage and, thus, satisfy LEED point requirements in those areas.
Still, most experts view energy modeling as both a science and an art. Beyond merely choosing software, it takes a licensed architect or engineer to harness its power and use it successfully. Though software may be the principal "tool" in the process, the design professional you employ must possess the skills and experience necessary to select the right data for the model, build that model thoughtfully, then analyze the results and develop recommendations.
Robert Bajko, AIA, LEED AP ID+C, is a principal with Cleveland-based HSB Architects + Engineers.
Construction Business Owner, December 2010
